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Patients who ate a “Mediterranean” diet rich in nuts or extra virgin olive oil as well as vegetables and wine had 30% fewer heart attacks, strokes, or deaths from cardiovascular disease than those that ate a diet that simply lowered their intake of dietary fat. The result, cardiologists say, is likely to change what doctors advise patients who are at risk of cardiovascular disease to eat. The study is being published in the New England Journal of Medicine and presented at the International Congress on Vegetarian Nutrition in Loma Linda, Calif.

Steven Nissen, chairman of the department of medicine at the Cleveland Clinic, called it “an outstanding study with broad societal implications,” noting that the benefit was as big as might be seen with the powerful cholesterol-lowering statin drugs that have become a mainstay of cardiology. He said the result shows “how science can dispel a widely held but fundamentally wrong public opinion”: in this case that an ultra-low-fat diet can make people heart attack proof. Harlan Krumholz, a cardiologist at Yale University and a Forbes contributor, called the result “game-changing.”

“The big issue here is not to cut the total amount of fat in the diet,” says Miguel Martinez-Gonzalez, Professor and Chair of the Department of Preventative Medicine at the University of Navarra and senior author of the study. “If you cut the amount of fat in the diet people will not comply. This is the advantage of the Mediterranean diet. It is high in fat, but it is healthy fat.”

The study carries much more scientific weight than most other studies of diet, which simply examine what it is that healthy people eat. A person who avoids red meat, for instance, might be doing all sorts of other things to remain healthy. What Martinez-Gonzalez and his colleagues did was to test the Mediterranean diet as if it were a drug, in a gold-standard randomized controlled clinical trial.

They recruited 7,447 men and women in Spain between the ages of 55 and 80 who had high blood pressure, high cholesterol, or other risk factors for heart disease but had not had heart problems yet. The researchers randomly assigned these patients to three groups, who were put on three different diets:

A Mediterranean diet high in vegetables, beans and other legumes, fruits, and fish, with at least 4 tablespoons of extra virgin olive oil a day. They were provided with a liter of the oil weekly for the use of their families. If they drank alcohol, they were told to consume at least seven glasses of wine a week. Cookies and other bakery treats, spreads like butter, and processed and red meats were discouraged.

A nearly identical Mediterranean diet that instead of extra-virgin olive oil included walnuts, almonds, and hazelnuts. People were advised to consume 30 grams of nuts a day, which they were given for free.

Patients in the control group were told to avoid fat, including removing any visible fat from food (cooling and scraping it off the top of soup, for instance). They were even to avoid fatty fish. These people received small gifts as part of the study.

The diets in the study. From the New England Journal of Medicine

There were 96 heart attacks, strokes, and cardiovascular deaths among the 2,543 people on the olive oil diet, 83 heart attacks, strokes, and cardiovascular deaths among the 2,454 patients who were on the nut diet, and 109 heart attacks, strokes, and cardiovascular deaths among the 2,450 people on the low-fat diet. When corrected for how long each of those people were on their respective diets, those who were on the nut or olive oil diets were 30% less likely to have a heart attack, stroke, or death related to cardiovascular disease than those on the low-fat diet.

That still means that you would have to put 333 people on a Mediterranean diet for five years in order to prevent a single heart attack, stroke, or cardiovascular death compared to a low fat diet. That’s because, in relatively healthy but high risk people, such mishaps are rare. Half the patients were already on ACE inhibitors to reduce their blood pressure and 40% took statins to reduce their cholesterol. But cardiovascular disease is still the leading cause of death. James Stein, a cardiologist at the University of Wisconsin School of Medicine and Public Health, said the study is “a big deal” and that although the absolute reduction in heart attacks and strokes is small, the diet is likely to have other benefits.

The study was not perfect. One big flaw was that at first, the people on the low-fat diet got less counseling than those who were on the diets rich in nuts or olive oil. The researchers realized this was a problem several years in, and changed the study design. Results on how the diets effected cholesterol levels or patients’ weight are not yet available.

But there’s other supporting evidence. A 2001 study had also shown a benefit for the Mediterranean diet. In 2006, part of the Women’s Health Initiative, a group of studies funded by the National Institutes of Health, found cutting fat from women’s diets did not prevent heart disease.

That still leaves big questions about exactly what kinds of fat are best. The saturated fats in meat, cheese, and butter are probably bad. The monounsaturated and polyunsaturated fats in vegetables, nuts, and fish are thought to be better. The big question now is whether some of these good fats are even better than others. Are the omega-3 fatty acids in salmon, for instance, better than the monounsaturated fats in olive oil? This study can’t answer that question.

What is clear is that there is now a pretty good blueprint for a diet to prevent heart disease. And while the study can really only be directly applied to people who are at high risk, Martinez-Gonzalez has some advice for even healthy, younger people like me: eat like the Mediterraneans do. “This is tasty,” he says, “and this is the future.”

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based on the diets, could be the dairy causing the heart attacks or the lack of counseling, or the lack of legumes. seems that after thousands of years of civilization and 50+ yrs of hi-tech science, that the fda and other countries’ govt entities could once and for all, focus long and hard on establishing with certainty what people should eat and not eat, and then be very clear about communicating it in schools. think of the implications! take it to the next step to focus big time on extending healthy lifespan dramatically for the masses. instead of signing up the next celebrity for “cheese does a body good” ads and helping promote “alcohol does a body good”.

Matthew, True be told this was not a clinical trial for their was not placebo group. This was a study conducted over a long period of time which subjects in all the different groups were not selected as to be a standardize control. Some were on medication for blood pressure, cholesterol, statins, etc… I am impressed that this undertaking does bring to light that yes food itself is something that can be as effective to the body as any drug and like anything supposedly good for you the key to success is moderation and balance. I hope people understand that the most people from the anthropological studies that brought the Med diet into the light understand that most people did not sit behind a desk rather they worked in farm fields or on fishing boats. This being the case sitting around and eating olive oil and drinking wine is not the end all be all. But you are what you eat…

That’s not what it says, Matt. The authors conclude that it’s just four additional tablespoons of olive oil or an ounce of nuts per day, as everyone in the study is Mediterranean and on the Mediterranean diet. And the result is an improvement of 2.6 in a thousand. You write about drug trials, Matt, is 2.6/1000 improvement in a 1% incidence really a “big deal”? Does the FDA approve drugs that help 1 out of every 400 people who take them?

By the way, if you read “On the immortality of television sets: “function” in the human genome according to the evolution-free gospel of ENCODE” in Genome Biology and Evolution, which I referenced above, you’ll see that one of the six reasons the authors feel the ENCODE group reached “absurd conclusions” is “(6) by emphasizing statistical significance rather than the magnitude of the effect.”

So these authors chose to study the effects of the Mediterranean diet in a study group in which both the test subjects and controls live in the Mediterranean and are on the Mediterranean diet. It’s like looking at the effect of a mutation in one cell line vs. a control cell line which also has the same mutation. And, when you see the same altered morphology in 109 out of 10,000 experimental cells vs. 96 out of 10,000 control cells, you conclude the difference of 13 cells per 10,000 is due to the mutation, which is in both the test cells and the controls. I do think it’s pretty absurd that they chose to test the diet in a background of people who lived in the Mediterranean and were on the same diet.

The only thing that adds any weight to this paper is the biomarker study you mention, but I’m skeptical about the results. I have a hard time believing that people living in the Mediterranean who eat lots of olive oil would show such a marked increase from simply adding an additional four tablespoons of olive oil to their daily diet. In addition, even if you believe the results, it’s hard to explain why there was no statistical difference in hydroxytyrosol levels between the control and experimental group through the first two to three year of the study (Fig. S4), when urine hydroxytyrosol levels have been shown to increase within 24 hours of olive oil consumption (http://www.nature.com/ejcn/journal/v57/n1/full/1601532a.html), or what the data means when, based on the biomarkers examined, there wasn’t a statistically significant difference in biomarker/olive oil consumption between the control and test group for about the first half of the five year study.

Furthermore, if you google “hydroxytyrosol” you’ll see most of the papers talk about it’s increase with alcohol consumption. And, if you read the conclusion of the paper I referenced, it says, “In conclusion, the reported data indicate that 24 h urine tyrosol and hydroxytyrosol are absorbed from sustained and moderate doses of virgin olive oil consumption. However, on the basis of our results, urinary tyrosol seems to be a better biomarker of virgin olive oil consumption that urinary hydroxytyrosol.”

So the gold standard paper chose a study population in which everyone was already on the diet they wanted to test. Their biomarker analysis didn’t show a significant difference in olive oil consumption during the first half of the study period, the marker they picked isn’t the best marker for looking at olive oil consumption, and they found an altered effect in 13-26 of 10,000 subjects.

I don’t think I’m overstating the problems with this study so much as your just hand-waving away significant issues in study design, execution and interpretation, because, like the authors and the people you spoke with, you seem more excited about confirming what you think you already know than concerned about whether the results are real.

Renaldo, I simply don’t have time to write an article length response to each of your comments — though I do admire your energy.

The idea that people in the modern Mediterranean eat the “Mediterranean diet” is pretty ludicrous, as another commenter mentioned. If you want to argue that the control diet raised people’s CV risk, that would mean the result is invalid. One assumption I do have is that both diets are probably better than the diet one would have outside a clinical trial.

Primary prevention trials have low event rates. And you’re getting the event rates wrong. You’re confusing patient-years with patients, which mis-states the results. They had to follow about 2,000 patients for years for every 100 heart attacks, strokes, and CV deaths. So yes, you’re only talking about 30 people being helped for every 2,000 who stay on this diet for 5 years compared to the control diet. That’s because the even you’re trying to prevent is rare. It’s also common, in the sense that just about everybody knows somebody who has had a heart attack or stroke.

It seems to me that you’re just going to keep talking unless I say this result wasn’t important and that the flaws were fatal. I have read the paper, I have talked to experts in the field, and I still think it is an important result.

I appreciate your arguments and responses. And while I am aware the study was following people over time, I don’t have unlimited time to critique the papers you talk about nor do I expect each of my real time comments to be completely accurate and not overridden when I find other references or look more closely at the data. I’m not the editor, I don’t have days/hours to devote to researching this paper and its references, and I’m doing this on the fly.

As far as your comment, “The idea that people in the modern Mediterranean eat the “Mediterranean diet” is pretty ludicrous…”, I couldn’t find the other comment you mentioned, but did it contain any references or data? Because, according to the International Olive Counsel http://www.internationaloliveoil.org/estaticos/view/131-world-olive-oil-figures , Spain consumes more than 15 times the amount of olive oil as Germany despite having roughly half the population (which means Spain has 30 times the per capita olive oil consumption as Germany). France has slightly more residents than Spain but consumes less than a sixth as much olive oil. But why let easily found facts get in the way of everything you already know? Based on these consumption numbers you are clearly correct and my claim that Spaniards in the control group still ate a lot of olive oil and adhere to a Mediterranean diet is “ludicrous” (and suggests you’ve never been to a tapas bar in Spain).

It’s true that it’s always easier to criticize grants and papers than to do the experiments yourself. However, because we are human and there will always be problems with any study are not reasons to be less critical of the methodology and results, or to accept published conclusions at face value.

And, just to be clear, I’m not trying to be argumentative just for the sake of it. If you take the totality of my criticisms, the fact that the study population was Mediterranean and the controls ate a lot of olive oil likely explains why there wasn’t a big difference in hydroxytyrosine levels through much of the study period. And the lack of a difference in olive oil consumption likely explains the paltry difference in events seen between the experimental and control groups. So if they had picked a better study population that didn’t normally consume a lot of olive oil, and possibly a better biomarker, they may have been able to show a much more convincing effect (well, unless you still want to argue that Spaniards don’t consume an order of magnitude more olive oil than non-Mediterranean EU countries). However, my suppositions and prognostications, and yours, are not relevant, and I think the numbers of events in this paper are too small and the experiments too poorly controlled to make much of an argument based on these results (and no, I’m not looking for you to agree with me, nor do I care if you don’t. However, if you’re going to say my arguments are “ludicrous”it would be nice if you could back it up with something more than”as someone else here said…”).

As to whether international attention matters, I think I may have said in a comment on an earlier article something along the lines that the more attention a paper gets the more it sets precedent and dogma. And the more people agree with something because “they believe” it’s correct without having solid data, the harder it is for contradictory studies to be funded and published in order to replace “what everyone already knows” with a more compelling model.

Furthermore, for obvious reasons, journalists tend to focus on articles in a select group of high impact journals. However, part of what I was trying to point out about Francis Collins and the ENCORE group is that political connections and self-promotion have at least as much if not a lot more to do with what gets published and where than the quality of the work (especially at NEJM and JAMA, which are not highly regarded amongst non-clinician scientists, though still highly coveted authorships for the effect they can have on your resume/career). I suspect politics and self-promotion have been the driving force in science and most human endeavors throughout history, which doesn’t make it right or productive.

And if there’s a tone of anger in my replies it’s because there are much better papers out there containing convincing data with huge game-changing implications for human health that are being ignored because their authors are focused more on, and are better at, science than self-promotion. And the big shots who have published 20 papers arguing they are now at step “D” (or that FTIs work in Progeria) don’t want to admit they’ve been wrong all along and go back to step “A” (well, at least not until everybody else is ready to make the move, too).

I think what I had said before was that every poorly designed “me too” study that gets published/promoted with questionable data supporting the accepted model adds one more brick to the wall preventing people with contradictory hypotheses from getting their experiments funded and studies published. Do I think that’s the case here? No, but the whole point is that good science isn’t about what you and I, editors and reviewers, or people in the (previous) middle ages, think and presume we already know.

Was this it: ” The predominate cooking oil is corn, soy, or canola. Olive oil is to expensive for the average person to use it to cook with (on some unidentified island) in the Med.”

You really said my argument was “ ludicrous” based on this unsupported opinion/personal observation (which is contradicted by the Olive Counsel reference above)? Do I need to remind you we’re talking about Spain, not some small island in the Med? And do I also need to remind you that the study participants didn’t receive and weren’t recommended to eat fresh greens and other components of a true “Mediterranean diet”, and that the primary focus of this article, as stated clearly by the authors, is the effect of olive oil and nuts?

Wow.

Sorry, but it sounds like you might be the one who is much more concerned with winning and internet argument than in actually be accurate or correct….